The present invention relates to the attenuation or damping of movement. More specifically the present invention regards method and apparatus for hydraulically damping motion between a first anchoring unit and a second anchoring unit.
The invention relates to a hydraulic damper bearing having a first anchoring unit and a second anchoring unit moveable in relation to the first anchoring unit; a spring component working between the first and the second anchoring unit; an operating chamber filled with damping fluid, and an equalizing chamber separated from the operating chamber and connected to the operating chamber via a fluid-conducting damping duct bordered by a duct wall, the volume of the operating chamber being changed during the relative motion of the first and second anchoring units, so that damping fluid is moved in the damping duct between equalizing chamber and operating chamber; and a displacing element arranged on the first anchoring unit, which displacing element extends into the operating chamber and is moveable with the first anchoring unit relative to the second anchoring unit.
An hydraulic damper bearing is described in German Patent Application 196 20 971 A1. Through such a bearing, low-frequency oscillations can be reduced on the basis of resonance reactions of the damping fluid in the damping duct. It is desirable in this context that the damping duct be as long as possible in order to increase the mass of the fluid moved in the damping duct. A long damping duct according to the method known from German Patent Application 196 20 971 A1 results in a large height of the hydraulic bearing. Such a height is then disadvantageous when the installation space is limited, as for example in an engine compartment.
An object of the present invention is to improve a hydraulic damper bearing in such a way that a long damping duct is achieved with a concomitant small height of the bearing.
On the basis of the design according to the present invention, the displacing element effects a lengthening of the damping duct without increasing the height of the bearing. The displacing element can be so constructed that it does not lengthen the duct in an elastically non-deflected state and lengthens the duct in a partially or fully elastically deflected state of the bearing. In the lengthened damping duct a relatively large amount of damping fluid is taken in, which increases the effectiveness of the resultant vibration damping.
According to an embodiment of the invention the displacing element is formed as a stop, which limits the movement between the first and second anchoring unit.
A particularly long damping duct is achieved in that some sections of the duct wall of the damping duct are formed by a support unit arranged on the second anchoring unit. In this manner a long damping duct can be formed, whose duct wall is formed in a first section by the support unit and in a second section by the displacing element, optionally together with the support unit.
According to another alternative embodiment of the present invention, the displacing element in a partially elastically deflected state of the bearing is adjacent to the second support unit with a first contact section, which forms a first section of the duct wall. It is thereby achieved that, e.g., the damping duct is lengthened via the displacing element with the bearing under nominal load, while this is not the case with the bearing under no load.
According to another alternative embodiment of the invention, the first contact section adjacent to the support unit is elastically deformed during the relative motion of the first anchoring unit with respect to the second anchoring unit. Consequently, a relative movement of the first and second anchoring units is only insignificantly or not at all hindered.
It has been proved to be advantageous that the first contact section extends to the second support unit in the axial direction of the bearing. Consequently, the contact section forms a duct wall oriented essentially parallel to the axial direction of the bearing.
According to another embodiment of the present invention, the displacing element has a second contact section extending in the radial direction of the bearing, which contact section forms a second section of the duct wall and is adjacent to the second anchoring unit. The second contact section is flexible in order to enable transverse movements of the first anchoring unit with respect to the second anchoring unit.
The manufacture of the hydraulic bearing is simplified in that the second anchoring unit in the area of contact with the second contact section is covered with a sealing cover layer, in particular made from elastomer.
A further improvement is achieved in that a duct outlet is formed in the first contact section that connects the damping duct to the operating chamber.
The strength of the displacing element is improved in that the displacing element has a support unit embedded in elastomer and manufacturing costs can be lowered by designing the displacing element as one piece.
A further improvement of vibration insulation can be achieved in that the displacing element in the operating chamber divides up a fluid duct bordering the spring component. The damping duct in the fluid duct together with the spring component working as a distending spring forms a system capable of vibration. This system can be tuned in a manner that results in the vibration damping of a certain frequency.
According to yet another alternative embodiment of the present invention, the fluid duct is connected to the operating chamber so the fluid can flow via an opening formed in the displacing element. Such an opening influences the resonance frequency of the damping fluid in the fluid duct. The opening can also be made lockable by the second contact section of the displacing element extending in the radial direction of the bearing. In this case, if a certain pressure difference between the damping duct and the fluid duct were exceeded, the second contact section would release the otherwise closed opening.
A connection between the fluid chamber and the operating chamber is advantageously produced by an opening which is provided in the second contact section and by the duct outlet, the duct outlet and the opening being arranged adjacent to each other in particular.
The vibration insulating qualities of the bearing can be further improved in that a partition exposed to damping fluid is provided to separate the operating chamber from the equalizing chamber. The partition can be formed in particular as a flexible membrane.
In this case a long damping duct is achieved in that at least some sections of the partition are radially enclosed by the damping duct.